21222126720 has 384 divisors, whose sum is σ = 75135191040. Its totient is φ = 5518098432.

The previous prime is 21222126719. The next prime is 21222126743. The reversal of 21222126720 is 2762122212.

It is a tau number, because it is divible by the number of its divisors (384).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 49011624 + ... + 49012056.

It is an arithmetic number, because the mean of its divisors is an integer number (195664560).

Almost surely, 2^21222126720 is an apocalyptic number.

21222126720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21222126720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37567595520).

21222126720 is an abundant number, since it is smaller than the sum of its proper divisors (53913064320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21222126720 is a wasteful number, since it uses less digits than its factorization.

21222126720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 652 (or 637 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

Adding to 21222126720 its reverse (2762122212), we get a palindrome (23984248932).

The spelling of 21222126720 in words is "twenty-one billion, two hundred twenty-two million, one hundred twenty-six thousand, seven hundred twenty".